This isn't about odor — honestly, if the species that invented indoor plumbing doesn't smell better, we're in serious trouble. But we have a far better sense of smell than Neanderthals did, and that reveals some crucial differences in our brains.

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Markus Bastir and Antonio Rosas of the Spanish Natural Science Museum (CSIC) used high-tech medical imaging to peer inside fossil skulls of both early modern humans and Neanderthals. Although the brain itself doesn't fossilize, we can deduce a lot of its structure from the cranium, which is shaped by the brain.

They identified two major areas where human and Neanderthal brains differ. The first is in the temporal lobe, which deals with language, memory, and social functions. This lobe is bigger in humans, which isn't a particularly surprising result. A more unexpected result is the olfactory bulb, which deals with smells and is 12% bigger in humans than Neanderthals. This means we probably had a significantly better sense of smell than our Neanderthal cousins.

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Our sense of smell is particularly important because it's the only sense that is directly wired to the brain - while visual or aural information has to pass through several filters, the chemical information from the nose is transferred straight to the brain. It's one of the oldest known senses in vertebrates, and it's a sense that never shuts down - even when we're asleep, we continue to breath and perceive odors. It's also closely connected with our memory systems, which is why smells can serve as powerful reminders of past events.

So why did we have the more powerful sense of smell? Some of it might have had to do with compensating for smaller hardware — Neanderthals had bigger faces and noses than we did, so our improved sense of smell might have simply leveled the playing field. It's also possible that a sense of smell was more important in Africa, where modern humans evolved, than it was in the Neanderthals' stomping grounds in Eurasia.

We can also look at the brain functions associated with the sense of smell, which neuroscientists have actually dubbed "higher olfactory functions" and include intuition, perception, and judgment. Olfactory information is also sent to regions of the brain involved in emotion, motivation, fear, memory, pleasure, and attraction. Any or all of these could be crucial to what made us uniquely human, and it all goes back to our surprisingly powerful noses. Of course, by that logic, dogs should probably be ruling the world, so this probably isn't the only explanation for humanity's success...